Commit 8f291889 authored by Al Viro's avatar Al Viro
Browse files

new helpers: vfs_create_mount(), fc_mount() 



Create a new helper, vfs_create_mount(), that creates a detached vfsmount
object from an fs_context that has a superblock attached to it.

Almost all uses will be paired with immediately preceding vfs_get_tree();
add a helper for such combination.

Switch vfs_kern_mount() to use this.

NOTE: mild behaviour change; passing NULL as 'device name' to
something like procfs will change /proc/*/mountstats - "device none"
instead on "no device".  That is consistent with /proc/mounts et.al.

[do'h - EXPORT_SYMBOL_GPL slipped in by mistake; removed]
[AV -- remove confused comment from vfs_create_mount()]
[AV -- removed the second argument]

Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 9bc61ab1

fs/namespace.c

+52 −24
Original line number Diff line number Diff line
@@ -941,12 +941,59 @@ static struct mount *skip_mnt_tree(struct mount *p) 
	return p;

}



/**

 * vfs_create_mount - Create a mount for a configured superblock

 * @fc: The configuration context with the superblock attached

 *

 * Create a mount to an already configured superblock.  If necessary, the

 * caller should invoke vfs_get_tree() before calling this.

 *

 * Note that this does not attach the mount to anything.

 */

struct vfsmount *vfs_create_mount(struct fs_context *fc)

{

	struct mount *mnt;



	if (!fc->root)

		return ERR_PTR(-EINVAL);



	mnt = alloc_vfsmnt(fc->source ?: "none");

	if (!mnt)

		return ERR_PTR(-ENOMEM);



	if (fc->sb_flags & SB_KERNMOUNT)

		mnt->mnt.mnt_flags = MNT_INTERNAL;



	atomic_inc(&fc->root->d_sb->s_active);

	mnt->mnt.mnt_sb		= fc->root->d_sb;

	mnt->mnt.mnt_root	= dget(fc->root);

	mnt->mnt_mountpoint	= mnt->mnt.mnt_root;

	mnt->mnt_parent		= mnt;



	lock_mount_hash();

	list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts);

	unlock_mount_hash();

	return &mnt->mnt;

}

EXPORT_SYMBOL(vfs_create_mount);



struct vfsmount *fc_mount(struct fs_context *fc)

{

	int err = vfs_get_tree(fc);

	if (!err) {

		up_write(&fc->root->d_sb->s_umount);

		return vfs_create_mount(fc);

	}

	return ERR_PTR(err);

}

EXPORT_SYMBOL(fc_mount);



struct vfsmount *vfs_kern_mount(struct file_system_type *type,

				int flags, const char *name,

				void *data)

{

	struct fs_context *fc;

	struct mount *mnt;

	struct vfsmount *mnt;

	int ret = 0;



	if (!type)
@@ -964,31 +1011,12 @@ struct vfsmount *vfs_kern_mount(struct file_system_type *type, 
	if (!ret)

		ret = parse_monolithic_mount_data(fc, data);

	if (!ret)

		ret = vfs_get_tree(fc);

	if (ret) {

		put_fs_context(fc);

		return ERR_PTR(ret);

	}

	up_write(&fc->root->d_sb->s_umount);

	mnt = alloc_vfsmnt(name);

	if (!mnt) {

		put_fs_context(fc);

		return ERR_PTR(-ENOMEM);

	}



	if (flags & SB_KERNMOUNT)

		mnt->mnt.mnt_flags = MNT_INTERNAL;

		mnt = fc_mount(fc);

	else

		mnt = ERR_PTR(ret);



	atomic_inc(&fc->root->d_sb->s_active);

	mnt->mnt.mnt_root = dget(fc->root);

	mnt->mnt.mnt_sb = fc->root->d_sb;

	mnt->mnt_mountpoint = mnt->mnt.mnt_root;

	mnt->mnt_parent = mnt;

	lock_mount_hash();

	list_add_tail(&mnt->mnt_instance, &fc->root->d_sb->s_mounts);

	unlock_mount_hash();

	put_fs_context(fc);

	return &mnt->mnt;

	return mnt;

}

EXPORT_SYMBOL_GPL(vfs_kern_mount);

include/linux/mount.h

+3 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ struct super_block; 
struct vfsmount;

struct dentry;

struct mnt_namespace;

struct fs_context;



#define MNT_NOSUID	0x01

#define MNT_NODEV	0x02
@@ -88,6 +89,8 @@ struct path; 
extern struct vfsmount *clone_private_mount(const struct path *path);



struct file_system_type;

extern struct vfsmount *fc_mount(struct fs_context *fc);

extern struct vfsmount *vfs_create_mount(struct fs_context *fc);

extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,

				      int flags, const char *name,

				      void *data);

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